This invention relates to a unique manufacturing technique involving the manufacturing embedment of one or more different kinds of component(s) into a heat, and applied-pressure, state-change receiving material, and to various types of resultant composite-material products produced thereby. The invention is particularly illustrated and described herein in relation to such a manufacturing technique which results in the creation of a variety of special-purpose panel structures which may be designed and configured to perform unique functions, and to possess unique composite characteristics that are useful, in many different end-use applications. While such panel structures serve well to illustrate the advantages and versatility of the invention, and accordingly have been chosen herein as appropriate invention-disclosure “vehicles”, but it should be clearly understood that non-panel, composite-material products are just as readily and advantageously produced in accordance with the practice and features of the invention.
Fundamentally the invention involves, in terms of a preferred manufacturing technique, the use of appropriate heat and a slight amount of simultaneously applied pressure, in the context of relative-motion pressure-“driving” a chosen, embeddable object into a mass of specially selected, temporarily flowable receiving material—a receiving material which readily accommodates a selectively reversible, non-destructive phase, or state, change from solid to liquid-flowability, thus to permit a resultant embedding of the chosen object in the material. With this fabrication approach, different kinds of useful objects, such as fabric living hinges, fastening devices, wiring, fluid-conduit structures, acoustic sensors, radioactivity sensors, thermal sensors, radio antennae, and many others may be incorporated securely in surrounding, dimensionally and configurationally stabilized support material for otherwise normal functioning therein. For example, a specialized vehicle door panel, shaped appropriately for a particular vehicle and use application, might, in accordance with the practice of the invention, be embedment-formed with an embedding-material main body carrying embedded fabric living hinges, embedded radio-transmission antenna wiring, electrical heating wiring, outwardly accessible fasteners adapted to accommodate the attachment of various external hardware, and so on.
An especially interesting feature is that small embedded objects, such as fasteners, having shapes which, on balance, lack, in an overall sense, axes and overall outer surfaces of revolution, such as hex-head and square-head nuts, may be embedded easily to become fully stabilized against loosening rotation within the selected embedding receiving material. Another interesting feature is that all aspects of embedment as practiced in accordance with the invention involve no material removal (and hence material waste) steps. A further feature to note is that embedment “binding” of an embedded object in place in the embedding receiving material occurs without the need for any auxiliary adhesives.
From the several specific illustrations given here, and hereinbelow, those skilled in the art will quickly appreciate the special utility of the present invention.
The selected, special material in which embedment takes place, also referred to as an embedding-and-object-receiving (EOR) material, preferably takes the form of a closed-cell, thermoformable foam material designated by the initials PET, which initials stand for the material known as polyethylene terephthalate. While different, specific thermoformable PET materials may well be chosen for use in the practice of this invention, we have found currently that a particularly preferred material is a polyethylene terephthalate, closed-cell, 6-24# foam product made by Sealed Air Corporation in Saddlebrook, N.J. An excellent body of technical information relating to this PET material, herein referred to also simply as PET, is available from the well known Internet source of wide-subject-matter general information known as Wikipedia, The Free Encyclopedia.
We have discovered that this PET material, through the appropriate introduction thereinto of appropriate heat of above about 300-degrees F., changes from a solid state to a “precursor” flowable state, without vaporization or flaming. This state change to initial material flowability then affords the opportunity, utilizing a very slight amount of relative-motion pressure, such as about 5-10-psi, easily to embed, into a portion of a mass of such heated PET, fully or partially, different kinds of objects, such as those just suggested above.
In accordance with practice of the invention, pressing of an object into the thus-heated, “now-flowable” PET mass region, causes PET material to yield appropriately, and entirely “locally”, to the “incoming” object, and to flow, compress, and “gradient densify” (to be explained shortly) in a zone of the PET region immediately surrounding and adjacent the embedded object. Preferably, though not necessarily, relative-motion embedment is progressed to the point where what then becomes the outermost, exposed portion of the embedded object is substantially flush with the particular surface of the PET mass into which embedment has taken place.
Significantly, with such zonal gradient densification occurring—a declining densification progressing outwardly from the embedded object into the surrounding PET material—the collective post-embedment volume of (a) the embedding PET material, and (b) of the portion, or the whole, of the embedded object, is substantially equal to the starting, selected (predetermined) volume of just the initial PET material alone. This feature, which is referred to herein as a volume maintenance feature, uniquely allows for precise, overall product-configuration, dimensional-tolerance control in a pre-planned, final, composite-material product simply through the pre-selection of the shape and size of the receiving PET material, and through relying on local-embedment-region, or zone, PET-material gradient densification to maintain and control final product size, etc., by not swelling the overall size of the original, starting mass of PET material.
Subsequent cooling of the PET material following heating and embedding of a selected object, we have observed, causes in all cases a good mechanical bond to establish between the PET material and the received object. This bond functions very successfully to anchor the received object with the PET material. Bond security is, of course, enhanced where the outside configuration of an embedded object has appropriate “protrusions” that cause the object to become positively “captured” within the embedding material.
With heating and flowing of the PET material during the embedment process, as just generally outlined, because of the relative-motion embedment pressure which is employed, the mentioned PET-material gradient-densification which then occurs creates an important PET continuous density gradient in the “immediately adjacent” zone of embedding PET material (i.e., immediately adjacent the embedded object), which gradient functions as a strengthened region around a received object. This region, which has a density gradient characterized by greater PET density directly next to the embedded object, “tapering” to “normal” PET density a short distance away from the embedded object, is without any internal, sharp-discontinuity, stress-risers. This strengthened region both provides a “hardened”, protective jacket adjacent the associated embedded object, and also acts like an internal, structural reinforcing element within the PET material per se—an “element” which is very useful in certain applications. For example, a vehicle door panel prepared with embedded winds or reverse-bend loops of radio antenna wire in accordance with practice of the invention, effectively possesses an invisible, wire-shape-matching internal stiffening brace.
Thus, we have determined that, utilizing such PET material, along with certain, selected “embedment” materials and objects, it is possible to create a wide range of extremely versatile and useful structures, such as panel structures, or panels, in which embedded objects, put into place in accordance with practice of this invention, can provide a number of useful, different, “embedded-object” functions. For example, and repeating in certain instances illustrations which have already been given, panels which may be used on various structures, such as buildings, boats, airplanes and other vehicles, may carry (a) embedded wiring for heating or radio-reception/transmission purposes (as well as for other purposes), (b) embedded fluid conduits for carrying various kinds of fluids, such as heating and cooling fluids, (c) different kinds of embedded sensors, such as acoustic sensors, heat sensors, radioactivity sensors, and so on, (d) various fabrics, for selected purposes, and (e) many other kinds of embedded objects, like various reception-attaching, or fastening, devices such as screw-threaded nuts, hardware hinges, etc.
With regard, as an illustration, to the embedment typically (although not exclusively) of relatively-small fastening devices, a very unique procedure proposed herein involves the practice of heating a to-be-received (embedded) fastening device to an appropriate temperature (such as around 300° F.), and then, utilizing modest, relative-motion pressure, simply advancing this heated device into the PET material to cause localized PET melting and flowing to accommodate embedment. In this specific practice approach of the invention, heat from the heated “to-be-embedded” device operates at the contact interface which develops and exists between this device and the receiving (embedding) PET material to cause an appropriate, local PET state change from solid to effectively flowable liquid.
In one modified form of the invention, the surface of a PET mass into which embedment is to take place is first covered with a fibre-strand-reinforced thermoformable plastic layer material, such as the material sold under the trademark Polystrand®, manufactured by a company having the same name, Polystrand, in Montrose, Colo. The plastic in this layer material is preferably made of polypropylene, and the reinforcing strands are preferably made of E-glass. This layer material, which may actually be formed from plural (such as about twelve) sub-layers of the same material, might typically have an overall thickness of about 0.16-inches. The plastic in this layer solid-to-flowability state-change preferably has a melting temperature like that of PET.
These and other features and advantages which are offered by the present invention will become more apparent shortly as the detailed description of the invention presented below is read in conjunction with the accompanying drawings.